What causes blue-green algae?
Blue-green algae need warm temperatures, sunlight, phosphorus and nitrogen to grow. Phosphorus and nitrogen are found in animal and human waste and in fertilizers. Some common ways for phosphorus and nitrogen to enter lakes and streams are from agricultural and lawn runoff and improperly located septic systems. In addition, Zebra mussels have been implicated as a factor promoting the growth of harmful algae blooms in the Great Lakes region, particularly for low-phosphorus inland lakes. How dangerous are blue-green algae? Blue-green algae are a natural part of all waterways. There are many species of blue-green algae. Not all are poisonous, however some can produce poisonous toxins. Is the water safe if it no longer appears to have a bloom in it? It is likely that some concentration of the toxin will be present for several weeks following a scum forming bloom, although generally the amount of toxin will be much less than was present with the scum formation. How does the toxin make peopl
